Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02363745 2001-11-26
COMPRESSOR SYSTEM
FIELD OF THE INVENTION
The present invention relates generally to a compressor system. More
particularly,
the present invention relates to an air/oil separator tank for use with an air
compressor.
BACKGROUND OF THE INVENTION
In conventional air compressor systems air is compressed in a compression
chamber or airend of a compressor, for example, by a set of rotary screws, and
a lubricant,
such as oil, is injected into the compression chamber and mixes with the
compressed air.
The oil is generally injected into the compression chamber for a number of
reasons
including cooling the air compressor system, lubricating bearings, balancing
axial forces
and sealing the rotary screws. Although using oil is essential for operating
these types of
air compressor systems, the oil must be removed from the stream of compressed
air before
the compressed air may be used downstream for pneumatic equipment and/or other
tools.
In such conventional air compressor systems, the compressed air and oil
mixture
discharged from the airend of the compressor flows with a high velocity into a
separator
tank where the air and oil of the air/oil mixture are caused to separate. The
separator tank
is usually cylindrical and the air/oil mixture is directed around an inner
wall of a
separation chamber. The combination of the centrifugal forces acting on the
air/oil
mixture and contact between the air/oil mixture and the inner wall of the
separation
chamber causes much of the oil to separate from the air/oil mixture, thereby
allowing
gravity to draw most of the oil downwardly into a lower portion of the
separation chamber
and also allowing the air to separate from the oil and flow upwardly into an
upper portion
of the separation chamber to achieve primary separation.
In these conventional air compressor systems, the compressed air, along with
some
fine oil droplets or mist entrained therein, passes through a separator
element placed
within the upper portion of the separation chamber, thereby coalescing most of
the
remaining oil in the air stream to achieve secondary separation before the
compressed air
is transferred out of the separator tank. The coalesced oil pools in a bottom
portion of the
separator element and is returned to the airend of the compressor by a
scavenging line.
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SUMMARY OF THE INVENTION
Conventional air compressor systems as described above typically include a lid
mounted on the separator tank to hold the separator element within the
separation chamber
of the separator tank. The separator element must be held in place because
there is an
upward force on the separator element due to the pressure differential between
the wet side
(outer) and dry side (inner) portions of the separator element. Conventional
air
compressor systems include an air exit port in the lid, and typically, a
minimum pressure
check valve (MPCV) assembly is operatively connected to the air exit port in
the lid.
After passing through the MPCV assembly, the compressed air is typically sent
to an
aftercooler, and then the cooled compressed air may be conveyed to pneumatic
equipment
and/or other tools. As can be appreciated by those skilled in the art, it is
generally
necessary to service or replace separator elements from time-to-time. In the
conventional
air compressor systems described above, before a separator element can be
serviced or
replaced, the air discharge hose and MPCV assembly, which usually includes
associated
1 S fittings, must be disconnected from the lid. This increases the time
required to service or
replace the separator element. Thus, there is a need for an air compressor
system which
eliminates the necessity of disconnecting the air discharge hose and MPCV
assembly from
the separator tank prior to servicing or replacing a separator element.
The conventional way to remove oil from inside a separator element of the air
compressor systems described above is to pass an independent scavenge tube
through the
lid mounted on the tank and down into an open area of the separator element.
The
scavenge tube extends to the bottom of the separator element and draws off the
excess oil
to prevent saturation of the separating media of the separator element.
Positioning the
scavenge tube through the lid and down into the open area of the separator
element can be
problematic. If the scavenge tube is too long, it may puncture the bottom of
the separator
element. If the scavenge tube is too short, it may not be sufficiently
effective in removing
the oil. In addition, before the separator element is replaced, the scavenge
tube must be
removed from the separator tank lid. Thus, there is a need for a scavenging
device which
is easy to install, which does not adversely affect the servicing or replacing
of a separator
element, and which also effectively removes oil from the bottom of the
separator element.
The present invention provides in one aspect thereof, a separator tank having
an air
exit port in a side wall of the tank, rather than in the lid of the tank as is
the case with
many known designs. Air from an air/oil mixture flows into an upper portion of
a
separation chamber of the tank, through a separator element positioned within
the upper
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portion of the separation chamber, and out the air exit port in the side wall
of the tank. An
MPCV assembly is operatively connected to the air exit port in the side wall
of the tank.
Because the MPCV assembly and air discharge hose are not attached to the lid
of the
separator tank, in order to service or replace the separator element, the lid
mounted on the
separator tank is simply removed or pivoted out of the way to allow access to
the separator
element, without having to first disconnect the discharge hose and MPCV
assembly.
The present invention provides in another aspect thereof, a separator element
hold
down mechanism between the separator element and the lid to position the
separator
element within the separation chamber and in spaced relation from the lid. Air
separated
from the air/oil mixture will flow through the separator element, towards the
lid, and out
the air exit port in the side wall of the separator tank.
The present invention provides in another aspect thereof, a separator element
oil
scavenge device which draws oil up off of the bottom of the separator element,
and which
transports the scavenged oil through the side wall of a separator tank. In one
embodiment
of the present invention, the scavenge device includes a tube which is
integrally formed
with the separator element. Once the tube is securely attached to the
separator element
and an end of the tube is located at a predetermined position relative to the
bottom of the
separator element, there is no need for independent adjustment of the tube
relative to the
bottom of the separator element and, as a consequence, no risk of making the
tube too long
or too short.
Other features and advantages of the invention will become apparent to those
skilled in the art upon review of the following detailed description, claims
and drawings in
which like numerals are used to designate like features.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an air compressor system embodying the present
invention.
FIG. 2 is a perspective view of a separator tank shown in FIG. 1.
FIG. 3 is a cross-sectional view of a separator tank assembly shown in FIG. 1.
FIG. 4 is a partial cross-sectional view of a portion of an alternative
embodiment of
a separator tank assembly of the present invention.
FIG. 5 is a partial cross-sectional view of a portion of an alternative
embodiment of
a separator tank assembly of the present invention.
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FIG. 6 is a partial cross-sectional view of a portion of an alternative
embodiment of
a separator tank assembly of the present invention.
FIG. 7 is a perspective view of the separator element hold down mechanism of
FIG. 6.
FIG. 8 is a partial cross-sectional view of a portion of an alternative
embodiment of
a separator tank assembly of the present invention.
FIG. 9 is a partial cross-sectional view of a portion of an alternative
embodiment of
a separator tank assembly of the present invention.
Before the embodiments of the invention are explained in detail, it is to be
understood that the invention is not limited in its application to the details
of construction
and the arrangements of the components set forth in the following description
or illustrated
in the drawings. The invention is capable of other embodiments and of being
practiced or
being carned out in various ways. Also, it is understood that the phraseology
and
terminology used herein are for the purpose of description and should not be
regarded as
limiting. The use of "including" and "comprising" and variations thereof
herein is meant
to encompass the items listed thereafter and equivalents thereof as well as
additional items
and equivalents thereof.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Illustrated in FIG. 1 is an air compressor system 10 embodying the present
invention. It should be understood that the present invention is capable of
use in other
compressor systems, and the air compressor system 10 is merely shown and
described as
an example of one such system.
The air compressor system 10 illustrated in FIG. 1 includes a compressor 14, a
motor 18, and a separator tank 22. Although the separator tank 22 as disclosed
herein is
used to separate oil from an air/oil mixture, it is contemplated that the
separator tank 22
may be used to separate a volume of gas from any mixed media combination,
including
any gas/liquid combination. In addition, it is contemplated that the
compressor 14 may be
any suitable compressor, such as an oil-flooded air compressor. However, for
the
purposes of describing the preferred embodiment, the compressor 14 is a rotary
screw
compressor.
The separator tank 22 may be constructed of any number of suitable materials.
However, in a preferred embodiment, the separator tank 22 is a cast separator
tank. Air
enters the compressor 14 and is compressed by rotary screws (not shown) found
within the
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compressor 14. Oil is injected into the compressor 14 to lubricate the rotary
screws and a
gearbox (not shown) which drives the rotary screws. The oil further serves as
a sealing
means for the compressor 14. The compressed air and some of the oil travel out
of the
rotary screws through an airend discharge opening of the compressor and into
an airend
inlet opening 26 (FIG. 2) in the separator tank 22. The separator tank 22
serves to separate
oil from the compressed air and also serves as an oil sump for the oil used to
lubricate the
rotary screws, the gearbox and other components. The compressed air and oil
enter the
separator tank 22 and are caused to undergo a cyclonic motion within the
separator tank
22. As the compressed air and oil are flung around an inner surface of the
separator tank
22, the oil will slide down the inner surface of the separator tank 22 and
collect in the
bottom of the separator tank 22, and the air will move up and out of the
separator tank 22
for further filtering, cooling and ultimate use.
Referring to FIG. 3, the separator tank 22 includes a side wall 30 and defines
a
separation chamber 34 having a lower portion 38 and an upper portion 42. The
lower
portion 38 of the separation chamber 34 serves as an oil reservoir or sump for
the oil that
is separated from the air/oil mixture introduced into the separation chamber
34 via channel
46 (see also FIG. 2) during the primary separation process. A channel 50
communicates
with the bottom of the lower portion 38 of the separation chamber 34. Pressure
within the
separator tank 22 forces the oil collected in the lower portion 38 of the
separation chamber
34 to flow through the channel 50 and back to the compression chamber of the
compressor
14 to lubricate the rotary screws, the gearbox and other components.
FIGS. 3-6 and 8-9 schematically illustrate separator elements 54 used in the
secondary separation process. Although the illustrated separator elements 54
may have
slightly different configurations, with reference to FIG. 9, each separator
element 54
generally has a cylindrical body comprising inner 55 and outer 56 perforate
metal shells,
filter media 57 sandwiched between the shells 55 and 56, an open top 58, a
closed bottom
62, and an internal passage (represented by arrow 64) where substantially oil-
free
compressed air flows from the separation chamber 34 of the separator tank 22.
During the
secondary separation process, oil pooled in the bottom 62 of the separator
element 54 will
be piped back to the compressor 14 via a scavenging device as described in
detail below.
It should be noted that the present invention is capable of use with many
different
separator elements, and the separator elements 54 are merely shown and
described as
examples of such separator elements.
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Referring now to FIG. 3, the separator element 54 is placed within the upper
portion 42 of the separation chamber 34. An annular flange 66 extends around
the top
portion 58 of the separator element 54. The separator tank 22 includes a ledge
70 which
extends circumferentially around an inner surface 74 of the side wall 30 of
the separator
tank 22. The flange 66 of the separator element 54 rests on the ledge 70 of
the side wall
30. It should be noted that when the separator tank 22 is a cast separator
tank, it is
preferable for the ledge 70 to be an integrally cast member of the separator
tank. As
previously explained, air from the air/oil mixture introduced into the
separation chamber
34 will flow upwardly into the upper portion 42 of the separation chamber 34
and through
the separator element 54.
The separator tank 22 includes an air exit port 78 in the side wall 30 of the
separator tank 22 for the air from the air/oil mixture that flows through the
separator
element 54. An MPCV assembly 82 is operatively connected, preferably
threadably
connected, to the air exit port 78. Lid 86 is mounted on the separator tank
22. When it is
desirable to service or replace the separator element 54, lid 86 is simply
removed or
pivoted out of the way to provide quick and easy access to the separator
element 54,
without having to first disconnect the MPCV assembly 82 from the air exit port
78.
In an alternative embodiment, a boss 90 (FIGS. 2 and 4) having a channel 94
(FIGS. 2 and 4) therethrough extends outwardly from the side wall 30 of the
separator tank
22. The boss 90 is arranged so that the air exit port 78' (FIG. 4) in the side
wall 30 aligns
with the channel 94 to provide an air exit passageway 98 (FIG. 4) out of the
upper portion
42 of the separation chamber 34. MPCV assembly 82 (FIG. 4) is operatively
connected to
the channel 94 of the boss 90. In a preferred embodiment, the separator tank
22 is a cast
separator tank and the boss 90 is an integrally cast member of the separator
tank 22.
Referring again to FIG. 3, during operation of the compressor system 10, an
upwardly acting resultant force within the separation chamber 34 is applied
against the
bottom 62 of the separator element 54. Thus, a separator element hold down
mechanism
102 is provided between the separator element 54 and the lid 86 to position
and hold the
separator element 54 within the separation chamber 34. The separator element
hold down
mechanism 102, which is in the shape of an annular spacer ring, engages the
flange 66 (or
flange 66' as shown in FIG. 8) of the separator element 54 to hold the
separator element
54 against the ledge 70 on the side wall 30 when the lid 86 is closed. The
separator
element hold down mechanism 102 positions the separator element 54 away from
the lid
86, and it also includes a plurality of apertures 106 (or 106' as shown in
FIG. 8) or holes
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which allow the air to flow through the separator hold down mechanism 102 to
reach the
air exit port 78 (or 78' as shown in FIG. 8) in the side wall 30 of the
separator tank 22.
The separator element hold down mechanism according to the present invention
may
comprise many different shapes and configurations, so long as it functions to
position and
hold the separator element within the separation chamber, and so long as it
allows the air
which travels through the separator element to reach the air exit port in the
side wall of the
separator tank.
For example, with reference to FIG. 5, the separator element hold down
mechanism 102' includes a plurality of bolts 110 which threadably extend
through the lid
86' and which engage the flange 66' of the separator element 54 to hold the
separator
element 54 against the ledge 70 on the side wall 30. Each bolt 110 includes an
O-ring seal
114 between itself and the lid 86' to better seal the air space provided
between the bottom
of the lid 86 and the top 58 of the separator element 54. Air flowing up
through the
separator element 54 simply changes direction and flows out of the air exit
port 78' in the
side wall 30 of the separator tank 22.
As another example, with reference to FIGS. 6-7, the separator element hold
down
mechanism 102" is a generally annular spacer ring 118 having a top ring 122, a
bottom
ring 126, and a plurality of columns 130 extending between the top 122 and
bottom 126
rings, thereby defining a plurality of air passages 134. The spacer ring 118
engages the
flange 66' of the separator element 54 to hold the separator element against
the ledge 70
on the side wall 30 when the lid 86 is closed. Air flowing up through the
separator
element 54 passes through the air passages 134 on its way to the air exit port
78'. In an
alternative embodiment, the annular spacer ring is a solid cast annular ring
having an
aperture therethrough to allow the air passing through the separator element
to reach the
air exit port.
Preferably, ledge 70 on the side wall 30 of the separator tank 22 includes an
annular groove 138 for receiving an O-ring seal 142 (see, e.g., FIG. 6). The O-
ring seal
142 is positioned between the flange 66' (or flange 66 as shown in FIG. 3) of
the separator
element 54 and the ledge 70 of the side wall 30 to provide an appropriate seal
and to
accommodate stack-up manufacturing/assembly tolerances in the separator tank
assemblies shown in FIGS. 3-6 and 8-9.
As mentioned above and with reference to FIG. 9, oil mist coalesced by the
secondary separator element 54 is drawn inward towards passage 64, runs down
inner
shell 55 and collects at the bottom 62 of the separator element 54. The
coalesced oil is
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drawn out of the bottom 62 of the separator element 54 by a separator element
oil
scavenge device 146. The scavenged oil is piped back to the compressor 14 for
use by the
compressor 14.
With continued reference to FIG. 9, the separator element oil scavenge device
146
includes a scavenge tube or pipe 150. The tube is preferably a metal tube but,
may be
made of other suitable materials, such as plastic. One end 154 of the tube 150
is located
near the bottom 62 of the separator element 54. The tube 150 extends up
through the
passage 64 of the separator element 54, and along and above the open end 58 of
the
separator element 54. Although not shown, a support member may extend across
the open
end 58 of the separator element 54. The tube 150 would then extend through the
support
member. The tube 150 extends back through the flange 66' of the separator
element 54.
The tube 150 also suitably extends through the spacer ring 118. The tube 150
is preferably
tack welded to either or both of the flange 66' and support member (not shown)
to locate
the end 154 of the tube 150 a predetermined distance from the bottom 62 of the
separator
element 54. Because the tube 150 is incorporated into the structure of the
separator
element 54, during assembly of the separator tank 22, no independent
adjustment of the
scavenge tube 150 is necessary to ensure that the tube 150 is spaced an
optimum distance
from the bottom 62 of the separator element 54. A channel 158 is provided in
the side
wall 30 of the separator tank 22. The channel 158 opens through the ledge 70
on the side
wall 30 and is adapted to receive a portion of the tube 150. An O-ring seal
162 is placed
around end 164 of the tube 150 which extends through the flange 66'. The
channel 158 is
also adapted to receive the O-ring seal 162 to provide an appropriate seal.
Upon assembly of the separator tank 22, the separator element 54 is placed
within
the separation chamber 34 such that the end 164 of the tube 1 SO extending
through the
flange 66' is received by the channel 158. As shown in FIG. 9, the~tube 150
may be used
as a handle for placing and removing the separator element 54 into and from
the separator
tank 22. To replace the separator element 54, the lid 86 is opened and the
separator
element 54 is removed without having to first disassemble the scavenge device
146. To
reinstall a separator element 54 into the separation chamber 34, a separator
element 54 and
its securely attached scavenge device is simply deposited within the
separation chamber 34
as described above. Once the lid 86 is closed, the separator hold down
mechanism will
hold the separator element in place.
FIG. 8 illustrates an alternative separator element oil scavenge device 146'
which
includes a scavenge tube 166, such as a Teflon tube. One end 170 of the tube
166 is
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connected to a fitting 174 found in the bottom 62 of the separator element 54
and the other
end 178 of the tube 166 is connected to a fitting 182 extending through a
channel 158' in
the side wall 30 of the separator tank 22.
Variations and modifications of the foregoing are within the scope of the
present
invention. It is understood that the invention disclosed and defined herein
extends to all
alternative combinations of two or more of the individual features mentioned
or evident
from the text and/or drawings. All of these different combinations constitute
various
alternative aspects of the present invention. The embodiments described herein
explain
the best modes known for practicing the invention and will enable others
skilled in the art
to utilize the invention. The claims are to be construed to include
alternative embodiments
to the extent permitted by the prior art.
Various features of the invention are set forth in the following claims.
